West Nile Risks Found Among the Homeless

By Ann Carrns

Spending lots of time outdoors raises your risk of contracting the West Nile virus, whether you’re walking in the woods because you like nature — or sleeping outside in the city because you’re homeless.

The study of 397 homeless people was undertaken after an analysis of patients hospitalized in Houston with West Nile virus between 2002, when the virus was first seen in Houston, and 2004, indicated the homeless were disproportionately represented. The city’s homeless population is estimated at 10,000.

Study participants, who were approached in shelters, soup kitchens and homeless camps, answered questions and gave blood samples for West Nile antibody testing. One in 14 subjects tested positive for the West Nile virus, compared with an estimated one in 22 people in the general population. Participants who had been homeless for more than a year, or who spent more than six hours a day outdoors, were at increased risk.

West Nile virus is transmitted to people by mosquitoes who feed on infected birds. The vast majority of people who contract West Nile have no symptoms at all, while about 20% develop flu-like symptoms, including fever and muscle aches. A small minority, however — less than 1% — develop a potentially fatal brain infection.

The findings aren’t all that shocking, since homeless people indeed spend a lot of time outside and are at risk for a host of ills. The Health Blog might suggest that the best solution would be to find homes for the homeless so they can spend more time indoors away from biting insects. But short of that, the study does suggest a practical step may help this vulnerable group: Giving them bug repellant. Many of the homeless used ineffective means of repelling mosquitoes, such as lighting candles. “Combining education with distribution of effective mosquito prevention aids such as mosquito repellent may help reduce the risk for [West Nile virus] infection and other mosquito borne diseases in this high-risk population,” the study notes.

One additional finding: Smoking marijuana was found to be a predictor of West Nile infection, although researchers found that link “difficult to explain.” It may be the bugs like the smoke — or, it could be that smoking reefer makes one less aggressive about swatting away mosquitoes. The link “deserves further investigation,” researchers conclude.